WYSIWYG (used as an adjective) is an acronym for: "What You See Is What You Get." When a computer program is WYSIWYG, then what you see on the screen is what will get printed out or displayed.
Back in the early days of personal computers, most programs were text-based which meant instead of seeing an indent of a line in a word processor, you had to type in a code (e.g., .indent5 or the like) and imagine what the text would look like. You could only confirm your image of it by printing it out. WYSIWYG programs were a huge improvement in the late 1980s because you could see what you were doing, as if you were typing on a typewriter.
Now WYSIWYG is used in the context of programs that help you to write code-based material such as web pages or wikis. These programs insert the code and the user only focuses on content and can see how the page will look.
Back in the early days of personal computers, most programs were text-based which meant instead of seeing an indent of a line in a word processor, you had to type in a code (e.g., .indent5 or the like) and imagine what the text would look like. You could only confirm your image of it by printing it out. WYSIWYG programs were a huge improvement in the late 1980s because you could see what you were doing, as if you were typing on a typewriter.
Now WYSIWYG is used in the context of programs that help you to write code-based material such as web pages or wikis. These programs insert the code and the user only focuses on content and can see how the page will look.